Performance analysis of short-side-chain Aquivion® perfluorosulfonic acid polymer for proton exchange membrane water electrolysis

An Aquivion® E87-12 S short-side-chain perfluorosulfonic acid (SSC-PFSA) membrane with equivalent weight (EW) of 870 g/eq and 120 μm thickness produced by Solvay Specialty Polymers was tested in a polymer electrolyte membrane water electrolyzer (PEMWE). For comparison, a benchmark Nafion® N115 membrane (EW 1100 g/eq) of similar thickness was investigated under similar operating conditions. Both membranes were tested in conjunction with in-house prepared unsupported IrO2 anode and carbon-supported Pt cathode electrocatalysts. The electrocatalysts consisted of nanosized IrO2 and Pt particles (particle size ~2-4 nm). Electrochemical tests showed better water splitting performance for the Aquivion® membrane and ionomer based membrane-electrode assembly (MEA) as compared to Nafion®. Lower ohmic drop constraints and smaller polarization resistance were observed for the electrocatalyst-Aquivion® ionomer interface indicating a better catalyst-electrolyte interface. A current density of 3.2 A cm−2 for water electrolysis was recorded at 1.8 V cell voltage and 90 °C with the Aquivion® based MEA. Some performance decay with time was observed indicating that the system requires further optimization of the interface characteristics.